For those in the dark, INFL stands for inflection and is a key component in Chomskyan analysis, being to the sentence what the noun is to the noun phrase, i.e. the notional head, as well as being a separate element from the actual verb phrase (VP).

Moreover, because traditional sentence analysis includes the functional categories (subject, object, adverbial etc) that the Chomskyan analysis deliberately eliminates, the resultant analysis reveals something about the meaning of the sentence – not just its form.

The developmental psychologists have been screaming about this for years, but the likes of Pinker et al haven't taken any notice, mainly because that would be the end of the Chomskyan programme in linguistics.

Even though vocabulary correlates closely with g, the Chomskyan idea of a language instinct seems fairly reasonable, since the vast majority of human beings who are not suffering an obvious organic problem such as deafness or severe retardation learn to speak a native tongue well enough to pass the famous Turing Test that has proven so difficult for artificial intelligence technologists.